<!DOCTYPE html>
<html>
<head>
    <title>WebSocket</title>
</head>
<body>
    <br>
    <input id="text" type="text"/>
    <button onclick="send()">send</button>
    <br>
    <button onclick="closeWebSocket()">close</button>
    <hr/>
    <div id="message"></div>
</body>

<script type="text/javascript">
    let websocket = null;
    //判断当前浏览器是否支持WebSocket
    if ('WebSocket' in window) {
        websocket = new WebSocket("ws://localhost:8080/ws");
    }
    else {
        alert('Not support webSocket')
    }

    //连接发生错误的回调方法
    websocket.onerror = function () {
        setMessageInnerHTML("WebSocket connect error");
    };

    //连接成功建立的回调方法
    websocket.onopen = function () {
        setMessageInnerHTML("WebSocket connect succeed");
    };

    //接收到消息的回调方法
    websocket.onmessage = function (event) {
        let now = getNowFormatDate();
        let data = now + " received" + '<br/>' + event.data;
        console.log(`received => ${event.data}`);
        setMessageInnerHTML(data);
    };

    //连接关闭的回调方法
    websocket.onclose = function () {
        setMessageInnerHTML("WebSocket close");
    };

    //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
    window.onbeforeunload = function () {
        closeWebSocket();
    };

    //将消息显示在网页上
    function setMessageInnerHTML(sendMessage) {
        document.getElementById('message').innerHTML += sendMessage + '<br/>';
    }

    //关闭WebSocket连接
    function closeWebSocket() {
        websocket.close();
    }

    //发送消息
    function send() {
        let message = document.getElementById('text').value;  //要发送的消息内容
        let now = getNowFormatDate();  //获取当前时间
        document.getElementById('message').innerHTML += (now + " Sender:" + '<br/>' + message) + '<br/>';
        websocket.send(message);
    }

    //获取当前时间
    function getNowFormatDate() {
        let date = new Date();
        let seperator1 = "-";
        let seperator2 = ":";
        let month = date.getMonth() + 1;
        let strDate = date.getDate();
        if (month >= 1 && month <= 9) {
            month = "0" + month;
        }
        if (strDate >= 0 && strDate <= 9) {
            strDate = "0" + strDate;
        }
        let currentdate = date.getFullYear() + seperator1 + month + seperator1 + strDate
            + " " + date.getHours() + seperator2 + date.getMinutes()
            + seperator2 + date.getSeconds();
        return currentdate;
    }
</script>
</html>